Thursday, December 23, 2010

Dec. 23 - End of Eastern Airmass Intrusion - Very hazy this morning. This is a view looking south from Las Cruces at 8:45 am. Normally you can see the other side of the valley in the distance.
Another view of the haze along the Organ Mountains at 9:13 am

LC airport temperatures 45F and dewpoint 32F, for a 61% RH. That can explain for some of the haze this morning. The core site PM10  concentration is 37 and PM2.5 is 16 µg/m3. The PM2.5/PM10 ratio is 0.43, which is higher than normal telling us a good size of the PM10 is in the PM2.5 mass compared to normal.

Another cold front will be approaching the region later today from the west bringing in a change in weather and some breezes. Below is the 5 am surface weather map showing our stationary front to the east of us and the approaching cold front to the west of us.
Looking at the particle counter on campus, we see the effects of the haze on particle size over time. The blue line is the 0.5 micron size particle counts and the other is the 10 micron size counts. The small particle counts peak overnight and the large particles peak when the wind starts to pick up in speed.
The particulates at the core site showed this morning fine particle event as well. The PM2.5/PM10 ratio went as high as 0.43 this morning. We're back to westerly and northwesterly winds now, bringing in cleaner air compared to this morning's southeast winds.
I'm also looking the NAAPS model output for 11 am today which shows a large area of sulfate continuing into Mexico.
It is easy to see the clouds from the passing front from today's timelapse camera from NMSU. It almost looked like rain but we didn't see any here.

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